Single Locker Thermal Enclosure System (STES) - PCG/VDA-2

Objectives

The objectives of this experiment were: (1) to produce large, well-ordered crystals of ten different proteins for use in x-ray diffraction studies and (2) to continue to develop the technology of microgravity protein crystal growth.

Shuttle-Mir Missions
STS-84

Approach
PCG/VDA-2 flew as a sortie mission in the Shuttle middeck locker. Protein crystal growth was achieved through vapor diffusion using a redesigned vapor diffusion apparatus. The VDA-2 apparatus consisted of four trays, each containing twenty experiment chambers. Each chamber contained a triple-barreled syringe; the two larger barrels are used to store protein and precipitant solutions, and the smaller third barrel was used during on-orbit activation. The experiment chambers were lined with a wicking material used to capture the reservoir solution. Mixing the protein solution with the precipitant was accomplished by a torque wrench ganging mechanism. By turning the torque wrench in one direction, the syringe piston was pushed toward the tip causing the solutions to move into the experiment chamber. These solutions mix to form a droplet. Water diffuses from the droplet through the vapor space into the more concentrated reservoir solution. As the protein droplet becomes more concentrated, protein crystals grow. Temperature control was provided by the Single Locker Thermal Enclosure System (STES); the temperature was set at 22 degrees Celsius for vapor diffusion.

The proteins involved in these experiments were Antibody fragment (Jel 1477), Trypanothione Reductase, NAD Synthetase Complex, HIV Capsid Protein, Lysozyme, Lectin from Cratylia mollis, Lectin KM+, Grass Pollen Allergen Phl pV, VEE Capsid Protein, and Turkey Egg White Lysozyme. A diverse set of protein crystals were studied on each mission. Following the Shuttle landing, the protein crystals were given to the respective investigators for post-mission x-ray diffraction analysis.

Results
Diffraction-sized crystals were obtained of five of the ten macromolecular compounds flown. Crystals of C. mollis lectin produced x-ray diffraction data that was 0.8 Angstroms better than the data previously collected from the best ground-grown crystals. This data contributed to the refinement of the three-dimensional structure of this protein.

Vapor diffusion protein crystal growth experiments conducted on STS-84 involved ten proteins in the third flight of the VDA-2 hardware. The experiments were successful in producing diffraction-sized crystals for five of the compounds flown and, the hardware performed flawlessly.

Earth Benefits
Knowledge gained in the protein crystal growth experiments contributed to enhance the understanding of the three-dimensional structure of several proteins. This information will be used to advance our fundamental understanding of protein interactions and in structure-based drug design projects to find new drugs to treat diseases.

Publications
None available at this time.

Principal Investigators
Lawrence J. Delucas, O.D., Ph.D.
University of Alabama

Co-Investigators
Louis Delbaere, Ph.D.
Yancho Devedijiev, Ph.D.
Juan Fonticella, Ph.D.
Ming Luo,Ph.D.
Karen Moore, Ph.D.
Glaucius Oliva, Ph.D.
Michael Spangfort, Ph.D.
Mark van der Woerd
Lan Zhou, Ph.D.

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Page last updated: 07/16/1999

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